Electromagnetically-operated fluid control valves are known in the art (see U.S. Pat. Nos. 5,076,326 and 4,998,559 as examples). In U.S. Pat. No. 5,076,326, a typical electromagnetic control valve, the armature of the magnet is coupled to or formed a part of the movable valve element. Such valves are useful for many purposes. They may be used to control a piston, or as disclosed in U.S. Pat. No. 5,076,326 and U.S. Pat. No. 4,998,559, one application has been for the control of the automatic transmission for motor vehicles. Signals from a computer, for example, are converted to the solenoid control signals for rapid and precise control. However, in these patents, as well as others of like genre, the electromagnet used to drive the armature and the control of valving element per se are rather massive, and the armature of the electromagnet is coupled to or formed as a part of the movable valve element.
The object of the present invention is to provide a fluid control valve which is more compact, has a smaller operating coil and wherein the armature of the electromagnet is not coupled to or formed as a part of the movable valve element per se.
The present invention further differs from the prior art in that the spool valve is actuated by hydraulic forces against a spring bias. The controlling hydraulic force is generated by controlling a small gate valve with the electromagnetic force of a small solenoid winding acting on the armature attached to the gate valve. This arrangement allows for a smaller winding because electromagnetic force required to move the small gate valve is much less than the electromagnetic force required if the armature is directly moving the spool valve against the spring force. Moreover, the arrangement allows for a smoother movement of the spool Valve because the control hydraulic flows through a small orifice generating a more gradual movement of the spool valve and the subsequent hydraulic fluid applied to hydraulic actuators which are being actuated. Finally, the arrangement allows for a smaller winding head portion of the solenoid outside of the valve body. The solenoid can be placed in a tighter configuration due to the smaller winding area.
One feature of the invention is that the outer housing is a sleeve which coacts with an inner sleeve having grooves to form hydraulic passages, thereby making the device easier to construct and smaller and more compact. Another feature of the invention is that a small gate valve in one end of the fluid control valve per se is operated by a small electromagnet to control hydraulic the fluid from the pump to actuate the main valve body against the spring pressure, the spring pressure always tending to close the valve.
Thus, the invention features a compact fluid pressure control valve solenoid including a gate valve comprising: outer and inner sleeves, said outer sleeve having ports connected thereto for the admission of pressurized fluid and the delivery of pressurized fluid from said pressure control valve to the work or back to a sump. The inner sleeve has formed therein at least a pair of fluid grooves, the outer sleeve acting in conjunction with said grooves in said inner sleeve to form passages for hydraulic fluid flow to said gate valve and from said main valve chamber.
The inner sleeve has a main valving chamber with the gate valve being formed at one end of the valving element chamber. A main valving element is in the main valving chamber. A main spring biases the main valving element closed with the removal of fluid from the main valving chamber through a vent port in the main valving chamber. A solenoid winding has an armature coupled to the gate valve element, a gate spring member biasing said gate valve element closed when said winding is deenergized. The main valve element has a piston head therein and arranged so that when said solenoid is energized, said gate valve opens to apply pressurized fluid to said piston head and open said main valving element and pass pressurized fluid to said work. The gate spring acting when said solenoid is deenergized to close said gate valve through the vent channel connected to said main valve chamber, thereby releasing the pressure on said main spring and thereby close the valve by moving the main valve element to a closed position.